1. Field of the Invention
The present invention relates to a silver halide photosensitive containing a high-boiling-point organic solvent which is excellent in such properties as solubility, dispersibility, and dispersion stability. More specifically, the present invention relates to a silver halide photosensitive material in which deterioration of color developability after storage and deterioration of storability of emulsions or latent images are alleviated.
Heretofore, a compound which is photographically useful and has low solubility in water was is incorporated into a hydrophilic colloid layer by being dissolved in a suitable oil droplet-forming agent, i.e., a high-boiling-point organic solvent, and thereafter being dispersed in a solution of a hydrophilic organo-colloid such as gelatin in the presence of a surfactant.
2. Description of the Related Art
A silver halide photosensitive material normally comprises a support having thereon a photosensitive layer and a non-photosensitive layer containing a photographically useful compound. In order to incorporate a compound which is photographically useful and has low solubility in water into the photosensitive layer and/or non-photosensitive layer, a process hitherto practiced comprises the steps of dissolving the photographically useful compound in a suitable oil droplet-forming agent, i.e., a high-boiling-point organic solvent, dispersing the solution containing the compound in a solution of a hydrophilic organo-colloid such as gelatin in the presence of a surfactant, and coating the dispersion on a support so that a hydrophilic organo-colloid layer containing the photographically useful compound is formed.
Since the high-boiling-point organic solvent, which is used for the formation of the hydrophilic organo-colloid layer, is used as a solvent for a hydrophobic compound in the formation of a constituent layer of a silver halide photosensitive material, and since the high-boiling-point organic solvent remains in the constituent layer after formation thereof, the high-boiling-point organic solvent is required to exhibit a wide range of performances as indicated below. That is, the high-boiling-point organic solvent has excellent capability to dissolve a photographically useful compound, as well as affinity for, dispersibility in, and dispersion stability in gelatin; the high-boiling-point organic solvent does not decrease the reactivity of the photographically useful compound (e.g., color developability of a coupler or redox reactivity of a redox compound such as a color mixing preventive); the high-boiling-point organic solvent can control the hue to be formed by a color-forming reaction to an optimum; the high-boiling-point organic solvent itself has excellent chemical stability; the high-boiling-point organic solvent does not accelerate decomposition of the photographically useful compound to be dispersed or yellowing of a white background due to decomposition; the high-boiling-point organic solvent does not accelerate fading of the dye to be formed due to light, heat, moisture, or atmosphere; the high-boiling-point organic solvent does not accelerate occurrence of colored stains which are caused by processing components remaining in the photosensitive material after processing; the high-boiling-point organic solvent does not adversely affect the storability of emulsions and latent images; and the high-boiling-point organic solvent is inexpensive and can be easily obtained.
Heretofore, phthalic ester was widely known as a high-boiling-point organic solvent for a silver halide photosensitive material. However, high-boiling-point organic solvents based on phthalic ester presented problems due to migration of the high-boiling-point organic solvent in the photosensitive material during storage.
The migration during storage can be inhibited by increasing of the molecular weight of the phthalic ester or by enhancement of hydrophobicity of the phthalic ester. But the high-boiling-point organic solvent having a larger molecular weight brings about the problem that reactivity of the photographically useful compound, for example color developability of a coupler, is reduced. Therefore, it has been difficult to attain inhibition of diffusion and preservation of reactivity at the same time.
Meanwhile, for further improvement of performances, development of new high-boiling-point organic solvents has been made. An example of such compounds is a compound having a plurality of ester linkages such as a dibenzoate. Examples of such compounds include the compounds described in, for example, Japanese Patent Application Laid-Open (JP-A) Nos. 1-101543, 2-43541, 2-77060, 3-191345, 3-192347, 4-146433, and 59-83154, and European Patent No. 969320. However, these compounds do not necessarily satisfy the requirements described above. In addition there is still, a need for attainment of the inhibition of the diffusion and the preservation of reactivity of the photographically useful compound.
At the same time, the development of a high-boiling-point organic solvent that causes little damage to the environment and can replace a phthalic ester has been desired.
A first object of the present invention is to provide a silver halide photosensitive material which uses a high-boiling-point organic solvent capable of sufficiently dissolving a compound having low solubility in water and providing excellent dispersibility and dispersion stability of the compound and which produces durable colored images and reduces the formation of colored stains. A second object of the present invention is to provide a silver halide photosensitive material in which the fogging and soft-toning of the emulsion during storage are alleviated. A third object of the present invention is to provide a silver halide photosensitive material in which the storability of latent images is improved. A fourth object of the present invention is to provide a silver halide photosensitive material in which undesirable effects that may be caused by the migration of a dispersing medium are inhibited. A fifth object of the present invention is to provide a silver halide photosensitive material in which problems due to conventional high-boiling-point organic solvents can be solved using an inexpensive high-boiling-point organic solvent. A sixth object of the present invention is to provide a silver halide photosensitive material in which the starting materials to be used for the manufacture cause little damage to the environment.
After close studies of a dibenzoate-based compounds and triester-based compounds, the present inventors have found that a compound having a specific structure enables the realization of the above-mentioned inhibition of the diffusion and the preservation of reactivity at the same time and satisfies all the requirements for a high-boiling-point organic solvent of a silver halide photosensitive material. Based on this finding, the inventors have achieved the present invention.
The problem described above can be solved by a silver halide photosensitive material containing at least one noncoloring compound represented by any one of the following general formulae (a) to (d): 
[In the general formula (a), Ra1 and Ra2 each independently represents an unsubstituted alkyl group having 1 to 10 carbon atoms. L1 represents a group represented by the following general formula (a2) or (a3). n and p each independently represents an integer of 1 to 5. Where L1 is a group represented by the general formula (a3), the total number of carbon atoms of Ra1, Ra2, Ra7, and Ra8 is 5 or greater.]
[In the general formula (a2), Ra3, Ra4, Ra5, and Ra6 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms and m represents an integer of 2 to 4. Ra3, Ra4, Ra5, and Ra6 may be the same as or different from each other. If m is 2 or greater, the total number of carbon atoms of Ra1, Ra2, Ra3, Ra4, Ra5, and Ra6 is 5 or greater.]
[In the general formula (a3), Ra7 and Ra8 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms and s represents an integer of 2 to 8. Ra7 and Ra8 may be the same as or different from each other.]
[In the general formula (b), L2 represents a group represented by the following formula (b2), (b3), or (b4)]
[In the general formula (b2), Rb1, Rb2, Rb3, and Rb4 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms with the proviso that the total number of carbon atoms of Rb1, Rb2, Rb3, and Rb4 is 5 or greater. In the general formula (b3), Rb5, Rb6, Rb7, Rb8, Rb9, and Rb10 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms with the proviso that the total number of carbon atoms of Rb5, Rb6, Rb7, Rb8, Rb9, and Rb10 is 6 or greater. In the general formula (b4), Rb11, Rb12, Rb13, Rb14, Rb15, Rb16, Rb17, and Rb18 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms with the proviso that the total number of carbon atoms of Rb11, Rb12, Rb13, Rb14, Rb15, Rb16, Rb17 and Rb18 is 2 or greater.]
[In the general formula (c), Rc1 represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. Rca, Rcb, Rc2, Rc3, Rc4, Rc5, Rc6, Rc7, and Rc8 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. x, y, and z each independently represents an integer of 0 to 5. If one or more of x, y, and z are 2 or greater, the Rc6s, the Rc7s, and the Rc8s may be the same as or different from each other, with the proviso that the total number of carbon atoms of Rca, Rcb, Rc1, Rc2, Rc3, Rc4, Rc5, Rc6, Rc7, and Rc8 is 3 or greater.]
[In the general formula (d), A, B, and D each independently represents an unsubstituted alkyl group having 1 to 10 carbon atoms or a group represented by the following general formula (d2). Rd1, Rd2, Rd3, Rd4, and Rd5 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms.]
[In the general formula (d2), Rd6 represents an unsubstituted alkyl group having 1 to 10 carbon atoms. t represents an integer of 0 to 5. If t is 2 or greater, the Rd6s may be the same as or different from each other, with the proviso that, in the formulae (d) and (d2), at least one of Rd1, Rd2, Rd3, Rd4, Rd5, and Rd6 is an unsubstituted alkyl group having 1 to 10 carbon atoms and that at least two of A, B, and D are each a group represented by the general formula (d2). If A, B, and D are each a group represented by the general formula (d2) and all of t are 0, the total number of carbon atoms of Rd1, Rd2, Rd3, Rd4, and Rd5 is 3 or greater.]
The noncoloring compound represented by any one of the formulae (a) to (d) is a good solvent for a photographically useful compound containing a hydrophobic organic material and exhibits an excellent dispersibility and dispersion stability in a binder such as gelatin capable of forming a colloid layer. Further, by contrast with a high-boiling-point organic solvent conventionally used in the preparation of a silver halide photosensitive material, the noncoloring compound described above can alleviate the decomposition of a photographically useful compound and the reduction in activity of a coupler contained in the photographically useful compound, and exhibits nondiffusiveness. Accordingly, the use of the noncoloring compound represented by any one of the formulae (a) to (d) makes it possible to provide a silver halide photosensitive material free from problems of formation of fogging and the like even after storage for a long time and capable of forming superior images.
According to the present embodiment of a silver halide photosensitive material, at least one noncoloring compound represented by any one of the following formulae (a) to (d) is used as a high-boiling-point organic solvent for dissolving components which constitute the silver halide photosensitive material and have low solubility in water.
The formulae (a) to (d) are explained in detail below.
First, the formula (a) is explained. 
In the general formula (a), Ra1 and Ra2 each independently represents an unsubstituted alkyl group having 1 to 10 carbon atoms. The unsubstituted alkyl group having 1 to 10 carbon atoms may be a branched or straight-chain alkyl group. Examples of the alkyl group include such groups as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and 2-ethylhexyl.
Among these groups, preferably Ra1 and Ra2 are each an unsubstituted alkyl group having 1 to 5 carbon atoms and more preferably an unsubstituted alkyl group having 1 to 3 carbon atoms. Preferably Ra1 and Ra2 are the same as each other.
n and p each independently represents an integer of 1 to 5. If n is 2 to 5, the plural of Ra1 may be the same as or different from each other, and, if p is 2 to 5, the plural of Ra2 may be the same as or different from each other. Preferably n and p are equal to each other, more preferably n and p are each 1 or 2, and most preferably n and p are each 1.
As to substitution positions of Ra1 and Ra2 on benzene rings, although the position may be any of an o-, m-, or p-position relative to a carbonyl group, the substitution positions are preferably the same for Ra1 and Ra2.
L1 represents a group represented by the following general formula (a2) or (a3). 
In the general formula (a2), Ra3, Ra4, Ra5, and Ra6 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. Examples of the unsubstituted alkyl group having 1 to 10 carbon atoms include the groups listed in the explanation of Ra1 and Ra2. Among these groups, preferably Ra3, Ra4, Ra5, and Ra6 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or an n-propyl group, and most preferably a hydrogen atom.
m represents an integer of 2 to 4. Accordingly, two or more of each of Ra3 to Ra6 are present. The plural of Ra3, Ra4, Ra5, and Ra6 may be the same as or different from each other. Preferably Ra3, Ra4, Ra5, and Ra6 are the same as each other. m is preferably 2 or 3 and most preferably 2.
If m is 2, the total number of carbon atoms of Ra1, Ra2, Ra3, Ra4, Ra5, and Ra6 is 5 or greater (preferably 5 to 20). Preferably the total number of carbon atoms of Ra1, Ra2, Ra3, Ra4, Ra5, and Ra6 is 6 or greater (preferably 6 to 10).
In the general formula (a3), Ra7 and Ra8 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. Examples of the unsubstituted alkyl group having 1 to 10 carbon atoms include the groups listed in the explanation of Ra1 and Ra2. Among these groups, preferably Ra7 and Ra8 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom, amethyl group, an ethyl group, an isopropyl group, or an n-propyl group, and most preferably a hydrogen atom.
s represents an integer of 2 to 8. Accordingly, two or more of each of Ra7 and Ra8 are present. Ra7 and Ra8 may be the same as or different from each other. If s is 5, preferably at least one of the five Ra7s and at least one of the five Ra8s are each an unsubstituted alkyl group having 1 to 10 carbon atoms. Preferably s is 2 to 4.
If L1 is a group represented by the general formula (a3), the total number of carbon atoms of Ra1, Ra2, Ra7, and Ra8 is 5 or greater (preferably 5 to 20). Preferably the total number of carbon atoms is 7 or greater (preferably 7 to 10). Most preferably the total number of carbon atoms is 9 or greater (preferably 9 to 10).
Preferably the structure of the compound represented by the general formula (a) is as follows.
That is, Ra1 and Ra2 each represents the same unsubstituted alkyl group having 1 to 3 carbon atoms. n and p are equal to each other and are each 1 or 2. L1 has the structure represented by the general formula (a2) or (a3). Ra3, Ra4, Ra5, and Ra6 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms. m is 2 or 3. If m is 2, the total number of carbon atoms of Ra1, Ra2, Ra3, Ra4, Ra5, and Ra6 is 5 or greater (preferably 5 to 20). Ra7 and Ra8 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms. s is 1,2,3 or 4.
More preferably the structure of the compound represented by the general formula (a) is as follows.
That is, Ra1 and Ra2 each represents the same group selected from a methyl group, an ethyl group, an isopropyl group, and an n-propyl group. n and p are equal to each other and are each 1. L1 has the structure represented by the general formula (a2) or (a3). Ra3, Ra4, Ra5, and Ra6 are each independently a hydrogen atom or alternatively a methyl group, an ethyl group, an isopropyl group, or an n-propyl group. m is 2 or 3. If m is 2, the total number of carbon atoms of Ra1, Ra2, Ra3, Ra4, Ra5, and Ra6 is 5 or greater (preferably 5 to 20). Ra7 and Ra8 are each a hydrogen atom or alternatively a methyl group, an ethyl group, an isopropyl group, or an n-propyl group. s is 2 or 4.
The molecular weight of the noncoloring compound represented by the general formula (a) is preferably 800 or less, more preferably 700 or less, further more preferably 600 or less, and most preferably 500 or less. The lower limit of the molecular weight is preferably 380 or more, more preferably 400 or more, and most preferably 420 or more. Particularly, if the molecular weight is specified by upper and lower limits, the molecular weight is preferably 380 to 800, more preferably 400 to 700, further more preferably 420 to 600, and most preferably 420 to 500.
Specific examples (i.e., exemplary compounds a-1 to a-33) of the noncoloring compound represented by the general formula (a) are given below. However, it should be noted that the present invention is not limited to these examples. 
Next, a method of synthesizing the noncoloring compound represented by the general formula (a) is described. The compound can be easily synthesized according to a conventionally known ester synthesis method indicated below. 
The compound represented by the general formula (a) can be synthesized by a reaction between a corresponding diol A or B and a benzoic acid derivative. Ra1, Ra2, Ra3, Ra4, Ra5, Ra6, Ra7, Ra8, m, s, and n in the formulae described above have the same respective meanings as in the general formula (a). L1 is a group obtained by removing hydrogen atoms from a diol which is a corresponding starting material in the reaction scheme. X is a hydroxyl group, a halogen atom, or a group known as a leaving group in the field of organic synthesis. If Xis ahydroxyl group, it is preferable that an acid catalyst is used and water that becomes a byproduct is removed to the outside of the reaction system by azeotropy or the like. If X is a halogen atom, it is preferable that a base in an amount of one equivalent ore more for each ester bond is used.
In the reactions described above, a single benzoic acid derivative is used. However, if the esterification is carried out successively or two kinds of benzoic acid derivatives are used, an asymmetric ester can be synthesized.
Next, the general formula (b) is explained. 
In the general formula (b), L2 represents a group represented by the following general formula (b2), (b3), or (b4). 
In the general formula (b2), Rb1, Rb2, Rb3, and Rb4 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. The unsubstituted alkyl group having 1 to 10 carbon atoms may be a branched or straight-chain alkyl group. Examples of the alkyl group include such groups as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and 2-ethylhexyl. Preferably Rb1, Rb2, Rb3, and Rb4 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 5 carbon atoms. More preferably Rb1, Rb2, Rb3, and Rb4 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 3 carbon atoms. Particularly preferably Rb1, Rb2, Rb3, and Rb4 are each a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or an n-propyl group. The total number of carbon atoms of Rb1, Rb2, Rb3, and Rb4 is 5 or greater (preferably 5 to 20). Preferably the total number of carbon atoms is 6 or greater (preferably 6 to 10). Most preferably the total number of carbon atoms is 8 or greater (preferably 8 to 10). 
In the general formula (b3), Rb5, Rb6, Rb7, Rb8, Rb9, and Rb10 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. Examples of the unsubstituted alkyl group include those listed in the explanation of Rb1, Rb2, Rb3, and Rb4. Preferably Rb5, Rb6, Rb7, Rb8, Rb9, and Rb10 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 5 carbon atoms. More preferably Rb5, Rb6, Rb7, Rb8, Rb9, and Rb10 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 3 carbon atoms. Particularly preferably Rb5, Rb6, Rb7, Rb8, Rb9, and Rb10 are each a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or an n-propyl group. The total number of carbon atoms of Rb5, Rb6, Rb7, Rb8, Rb9, and Rb10 is 6 or greater (preferably 6 to 20). Preferably the total number of carbon atoms is 7 or greater (preferably 7 to 10). Most preferably the total number of carbon atoms is 8 or greater (preferably 8 to 10). 
In the general formula (b4), Rb11, Rb12, Rb13, Rb14, Rb15, Rb16, Rb17, and Rb18 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. Examples of the unsubstituted alkyl group include those listed in the explanation of Rb1, Rb2, Rb3, and Rb4. Preferably Rb11, Rb12 Rb13, Rb14, Rb15, Rb16, Rb17, and Rb18 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 5 carbon atoms. More preferably Rb11, Rb12, Rb13, Rb14, Rb15, Rb16, Rb17, and Rb18 are each a hydrogen atom or an unsubstituted alkyl group having 1 to 3 carbon atoms. Particularly preferably Rb11, Rb12, Rb13, Rb14, Rb15, Rb16, Rb17, and Rb18 are each a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or an n-propyl group. The total number of carbon atoms of Rb11, Rb12, Rb13, Rb14, Rb15, Rb16, Rb17, and Rb18 is 2 or greater (preferably 2 to 20). Preferably the total number of carbon atoms is 3 or greater (preferably 3 to 10). Most preferably the total number of carbon atoms is 4 or greater (preferably 4 to 10).
The noncoloring compound represented by the general formula (b) does not form a dye by a coupling reaction with the oxidized form of a developing agent and therefore is a noncoloring compound. Accordingly, this noncoloring compound does not have a coupler residue in the molecular structure thereof.
The molecular weight of the noncoloring compound represented by the general formula (b) is preferably 800 or less, more preferably 700 or less, further more preferably 600 or less, and most preferably 500 or less. On the other hand, the molecular weight of the noncoloring compound represented by the general formula (b) is preferably 340 or more, more preferably 360 or more, and most preferably 370 or more. Particularly, if the molecular weight is specified by upper and lower limits, the molecular weight is preferably 340 to 800, more preferably 360 to 700, furthermore preferably 370 to 600, and most preferably 370 to 500.
Specific examples (i.e., exemplary compounds b-1 to b-28) of the noncoloring compound represented by the general formula (b) are given below. However, it should be noted that the present invention is not limited to these examples. 
The noncoloring compound represented by the general formula (b) can be easily synthesized according to an ester synthesis method indicated below. 
The compound represented by the general formula (b) can be synthesized by a reaction between a corresponding diol A, B, or C and a benzoic acid derivative. Rb1 to Rb18 in the formulae described above have the same respective meanings as in the general formulae (b), (b2), (b3), and (b4). L2 is a group obtained by removing hydrogen atoms from a diol which is a corresponding starting material in each reaction scheme. X is a hydroxyl group, a halogen atom, or a group known as a leaving group in the field of organic synthesis. If X is a hydroxyl group, it is preferable that an acid catalyst is used and water that becomes a byproduct is removed to the outside of the reaction system by azeotropy or the like. If X is a halogen atom, it is preferable that a base in an amount of one equivalent ore more for each ester bond is used.
Next, a compound represented by the general formula (c) is explained. 
In the general formula (c), Rc1 represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. The unsubstituted alkyl group having 1 to 10 carbon atoms may be a branched or straight-chain alkyl group. Examples of the alkyl group include such groups as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and 2-ethylhexyl. Among these groups, a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-pentyl groups are preferable.
Rca, Rcb, Rc2, Rc3, Rc4, Rc5, Rc6, Rc7, and Rc8 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. Among these, a hydrogen atom or an unsubstituted alkyl group having 1 to 5 carbon atoms is preferable and a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms is more preferable.
Among Rca, Rcb, Rc2, Rc3, Rc4, and Rc5, a hydrogen atom is preferable. Among Rc6, Rc7, and Rc8, a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, an n-propyl group, an n-butyl group, and the like are preferable.
x, y, and z each independently represents an integer of 0 to 5. It is preferable that x, y, and z each represents an integer of 0 to 2. It is more preferable that x, y, and z each represents 1. Further, it is preferable that Rc6, Rc7, and Rc8 each represents the same group in view of manufacture and cost.
The upper limit of the molecular weight of the noncoloring compound represented by the general formula (c) is preferably 800 or less, and more preferably 700 or less. The lower limit of the molecular weight is preferably 450 or more, more preferably 480 or more, and most preferably 500 or more.
If the molecular weight is specified by upper and lower limits, the molecular weight is preferably 450 to 800, more preferably 480 to 800, further more preferably 500 to 800, and most preferably 500 to 700.
Specific examples (i.e., exemplary compounds c-1 to c-22) of the noncoloring compound represented by the general formula (c) are given below. However, it should be noted that the present invention is not limited to these examples. 
Next, a method of synthesizing the noncoloring compound represented by the general formula (c) is described. The compound can be easily synthesized according to a conventionally known ester synthesis method indicated below. 
The compound represented by the general formula (c) can be synthesized by a reaction between a corresponding triol and benzoic acid derivatives. Rc1 to Rc8, Rca, Rcb, x, y, and z in the reaction formulae described above have the same respective meanings as in the general formula (c). X is a hydroxyl group, a halogen atom, or a group known as a leaving group in the field of organic synthesis. If X is a hydroxyl group, it is preferable that an acid catalyst is used and water that becomes a byproduct is removed to the outside of the reaction system by azeotropy or the like. If X is a halogen atom, it is preferable that a base in an amount of one equivalent ore more for each ester bond is used.
The example described above indicates a reaction in which 3 kinds of compounds are used as benzoic acid derivatives. But the reaction may be carried out using 2 kinds of benzoic acid derivatives or using one kind of benzoic acid derivative.
Next, a compound represented by the general formula (d) is explained. 
In the general formula (d), A, B, and D each independently represents an unsubstituted alkyl group having 1 to 10 carbon atoms or a group represented by the general formula (d2).
The unsubstituted alkyl group having 1 to 10 carbon atoms represented by A, B, or D may be a branched or straight-chain alkyl group. Specific examples of the alkyl group include such groups as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and 2-ethylhexyl.
Among these groups A, B, and D, an unsubstituted alkyl group having 1 to 5 carbon atoms is preferable and an unsubstituted alkyl group having 1 to 3 carbon atoms is more preferable.
In the general formula (d), Rd1, Rd2, Rd3, Rd4, and Rd5 each independently represents a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms.
Examples of the unsubstituted alkyl group having 1 to 10 carbon atoms include those listed in the explanation of A, B, and D. Among Rd1, Rd2, Rd3, Rd4, and Rd5, a hydrogen atom or an unsubstituted alkyl group having 1 to 5 carbon atoms is preferable and a hydrogen atom or an unsubstituted alkyl group having 1 to 3 carbon atoms is more preferable.
In the general formula (d2), Rd6 represents an unsubstituted alkyl group having 1 to 10 carbon atoms. Examples of the unsubstituted alkyl group having 1 to 10 carbon atoms include those listed in the explanation of A, B, and D. Among Rd6, an unsubstituted alkyl group having 1 to 5 carbon atoms is preferable and an unsubstituted alkyl group having 1 to 3 carbon atoms is more preferable.
In the general formula (d2), t represents an integer of 0 to 5. If t is 2 or greater, the Rd6s may be the same as or different from each other. Among t, 0, 1, or 2 is preferable and 0 or 1 is more preferable.
In the general formulae (d) and (d2), at least one of Rd1, Rd2, Rd3, Rd4, Rd5, and Rd6 is an unsubstituted alkyl group having 1 to 10 carbon atoms. At least two of A, B, and D are each a group represented by the general formula (d2). Preferably all of A, B, and D are each a group represented by the general formula (d2).
If all of A, B, and D are each a group represented by the general formula (d2) and t is 0, the total number of carbon atoms of Rd1, Rd2, Rd3, Rd4, and Rd5 is 3 or greater.
Among the structures represented by the general formula (d), it is preferable that all of A, B, and D are each a group represented by the general formula (d2); Rd1, Rd2, Rd3, Rd4, and Rd5 are each independently a hydrogen atom or an unsubstituted alkyl group having 1 to 3 carbon atoms; t is 0 or 1; Rd6 is an unsubstituted alkyl group having 1 to 3 carbon atoms; and at least one of Rd1, Rd2, Rd3, Rd4, Rd5, and Rd6 is an unsubstituted alkyl group having 1 to 3 carbon atoms, with the proviso that the total number of carbon atoms of Rd1, Rd2, Rd3, Rd4, and Rd5 is preferably 3 or greater if each t is 0.
Among the preferred structures described above, it is more preferable that all of A, B, and D are each a group represented by the general formula (d2); Rd1, Rd2, Rd3, Rd4, and Rd5 are each independently a hydrogen atom or alternatively a methyl group, an ethyl group, or an n-propyl group; t is 0 or 1; Rd6 is a methyl group, an ethyl group, or an n-propyl group; and at least one of Rd1, Rd2, Rd3, Rd4, Rd5, and Rd6 is a methyl group, an ethyl group, or an n-propyl group, with the proviso that the total number of carbon atoms of Rd1, Rd2, Rd3, Rd4, and Rd5 is preferably 3 or greater if each t is 0.
Among the more preferred structures described above, it is particularly preferable that all of A, B, and D are each a group represented by the general formula (d2); Rd1, Rd2, Rd3, Rd4, and Rd5 are each independently a hydrogen atom or a methyl group; t is 0 or 1; Rd6 is a methyl group; and at least one of Rd1, Rd2, Rd3, Rd4, Rd5, and Rd6 is a methyl group, with the proviso that the total number of carbon atoms of Rd1, Rd2, Rd3, Rd4, and Rd5 is particularly preferably 3 or greater.
Among the particularly preferred structures described above, one of the most preferred structures is such that all of A, B, and D are each a group represented by the general formula (d2); t is 0; Rd1, Rd2, Rd3, Rd4, and Rd5 are each independently a hydrogen atom or a methyl group; and at least one of Rd1, Rd2, Rd3, Rd4, Rd5, and Rd6 is a methyl group, with the proviso that the total number of carbon atoms of Rd1, Rd2, Rd3, Rd4, and Rd5 is particularly preferably 3 or greater.
Another of the most preferred structures is such that all of A, B, and D are each a group represented by the general formula (d2); t is 1; Rd1, Rd2, Rd3, Rd4, and Rd5 are each independently a hydrogen atom or a methyl group; and Rd6 is a methyl group, with the proviso that all of A, B, and D are preferably the same.
The molecular weight of the noncoloring compound represented by the general formula (d) is preferably 400 or more and 800 or less, more preferably 410 or more and 700 or less, and particularly preferably 430 ormore and 600 or less.
Specific examples (i.e., exemplary compounds d-1 to d-37) of the noncoloring compound represented by the general formula (d) are given below. However, it should be noted that the present invention is not limited to these examples. 
The compound represented by the general formula (d) can be easily synthesized according to a conventionally known ester synthesis method indicated below: 
The compound represented by the general formula (d) can be synthesized by a reaction between a corresponding triol and carboxylic acid derivatives having partial structures A, B, and D.
Rd1, Rd2, Rd3, Rd4, Rd5, A, B, and D in the general formulae in the synthesis scheme described above have the same respective meanings as in the general formula (d).
X in the general formulae in the synthesis scheme is a hydroxyl group, a halogen atom, or a group known as a leaving group in the field of organic synthesis. If X is a hydroxyl group, it is preferable that an acid catalyst is used and water that becomes a byproduct is removed to the outside of the reaction system by azeotropy or the like. If X is a halogen atom, it is preferable that a base in an amount of one equivalent ore more for each ester bond is used.
The synthesis scheme described above shows an example in which 3 kinds of compounds are used as carboxylic acid derivatives. But the reaction may be carried out using 2 kinds of carboxylic acid derivatives or using one kind of carboxylic acid derivative.
The noncoloring compounds represented by the general formulae (a) to (d) do not form a dye by a coupling reaction with the oxidized form of a developing agent and therefore are noncoloring compounds. Accordingly, these noncoloring compounds do not have a coupler residue in the molecular structures thereof.
The amount to be used of the compound represented by any of the general formulae (a) to (d) may vary according to purpose. The amount to be used is preferably 0.2 mg to 20 g, more preferably 1 mg to 5 g, based on 1 m2 of the photosensitive material. Further, the ratio by mass of the compound to a photographically useful reagent such as a coupler is generally in the range of 0.1 to 10 and preferably in the range of 0.1 to 2.
The ratio by mass of the compound represented by any of the general formulae (a) to (d) to the dispersing medium of a dispersion containing a photographically useful reagent such as a coupler is preferably within the range of 4 to 0.1 and more preferably within the range of 1.0 to 0.2.
Examples of the photographically useful reagents excluding a coupler include a photo-fading inhibitor, a dark-heat fading inhibitor, a stain inhibitor, a color mixing preventive, a UV absorbing agent, a dye (e.g., for irradiation inhibition or halation inhibition), a compound which releases a photographically useful compound at the time of processing (e.g., a so-called blocked compound, DIR hydroquinone, dye-releasing redox compound, or the like), and so on. Examples of the dispersing medium include gelatin that is a typical dispersing medium and a hydrophilic polymer such as polyvinyl alcohol. Further, various compounds may be incorporated according to purposes besides the above-mentioned photographically useful compounds.
Compounds represented by the general formulae (a) to (d) may be used singly or in combinations of two or more. Where two or more of the compounds are used in combination, it is preferable to use a mixture of position isomers (e.g., a mixture of position isomers with respect to Ra1 and Ra2 in the general formula (a)) from the standpoint of solubility.
The compounds represented by the general formulae (a) to (d) can be added to a silver halide photosensitive material in the same way as in the addition of a conventionally known high-boiling-point solvent to a silver halide photosensitive material.
The compound represented by any of the general formulae (a) to (d) maybe added to any hydrophilic colloid layer to which a photographically useful compound will be added. Preferably the compound is added to at least one hydrophilic colloid layer. More specifically the compound is added to at least one layer selected from a non-photosensitive layer, a red-sensitive emulsion layer, a green-sensitive emulsion layer, and a blue-sensitive emulsion layer.
The compounds represented by the general formulae (a) to (d) maybe used in combinations with conventionally known high-boiling-point organic solvents that are out of the scope defined by the general formulae (a) to (d). Where these conventionally known high-boiling-point organic solvents are also used, the ratios by mass of compounds represented by the general formulae (a) to (d) to the total of the high-boiling-point organic solvents are preferably 10% or more and more preferably 30% or more up to 100%.
Examples ((1) to (153)) of the conventionally known high-boiling-point organic solvents that can be used together with the compounds represented by the general formulae (a) to (d) are given below:
The silver halide photosensitive material in the present embodiment can be made by coating on a support as a photosensitive layer at least one yellow-developing silver halide emulsion layer, at least one magenta-developing silver halide emulsion layer, and at least one cyan-developing silver halide emulsion layer. For example, in a color print paper for general use, a subtractive-process color reproduction can be carried out by the incorporation of a color coupler designed to form a dye whose color is complementary to the light to which the silver halide emulsion is sensitive.
It is preferable that the noncoloring compound represented by any of the formulae (a) to (d) is added, together with a photographically useful compound, to any hydrophilic colloid layer. The layer, which contains the compound represented by any of the formulae (a) to (d), may be a photosensitive layer or a non-photosensitive layer. For example, if the silver halide photosensitive material of the present invention is a photosensitive material for full-color image formation, the noncoloring compound represented by any of the formulae (a) to (d) is added to at least one layer selected from a non-photosensitive layer, a red-sensitive emulsion layer, a green-sensitive emulsion layer, and a blue-sensitive emulsion layer.
Each photosensitive layer is formed by coating on a support a coating liquid prepared by dispersing a silver halide emulsion containing silver halide grains and an emulsion containing a hydrophobic compound (i.e., a photographically useful compound) such as a coupler in a binder such as gelatin. Likewise, a non-photosensitive layer is formed by coating, for example, on a support a coating liquid prepared by dispersing an emulsion containing a photographically useful compound such as a UV absorbing agent or a color mixing preventive in a binder such as gelatin. The compound represented by any of the formulae (a) to (d) can be used as a high-boiling-point organic solvent for use in the preparation of the emulsions described above. The use of this compound makes it possible to prepare a silver halide photosensitive material capable of producing durable images and diminishing the occurrence of colored stains while ensuring sufficient solubility, dispersibility, and dispersion stability of essential components having low solubility in water. Further, the use of this compound makes it possible to reduce the fogging and soft-toning during storage of the raw photosensitive material and to raise the storability of latent images. Furthermore, the use of this compound makes it possible to effectively avoid the intra-layer migration of dispersing medium during storage and to inhibit adverse effects accompanying the migration of the dispersing medium on the silver halide photosensitive material (i.e., enhancement of raw storability). In addition, the noncoloring compound (i.e., high-boiling-point organic solvent) represented by any of the formulae (a) to (d) is inexpensive and can be easily obtained and causes little damage to the environment. Therefore, this noncoloring compound is useful as a compound that replaces a high-boiling-point organic solvent based on a phthalic ester.
The emulsion described above further contains other components, for example, a color-developing coupler and a dispersing medium such as gelatin. These components are described later.
In the preparation of the silver halide photosensitive material, particularly a color print paper for general use, silver halide grains are spectrally sensitized by respective spectral sensitizing dyes to obtain blue-sensitive, green-sensitive, and red-sensitive emulsions in the process of the preparation of silver halide emulsions. The silver halide photosensitive material can be prepared by coating these emulsions in the order listed previously on a support. But an order different from this order may also be employed. For example, from the standpoint of rapid processing, the uppermost layer is preferably a photosensitive layer composed of silver halide grains having the largest average grain size. Alternatively, from the standpoint of storability under a condition irradiated with light, the lowermost layer is preferably a magenta-developing photosensitive layer.
Besides, the relationship between a photosensitive layer and a color to be developed may be different from the one described above, and at least one infrared-sensitive silver halide emulsion layer can also be used.
The silver halide grains to be used in the present invention include silver chloride, silver chlorobromide, silver iodobromide, silver chloroiodobromide, and the like. The use of silver chloride, silver chlorobromide, or silver chloroiodobromide grains, each having a silver chloride content of 90 mol % or greater, is preferable. The silver chloride content is preferably 95 mol % or greater, more preferably 95 to 99.9 mole %, and most preferably 98 to 99.9 mole %. In particular, in order to shorten the time required for development processing in the present invention, silver halide grains, which contain substantially no silver iodide and are composed of silver chlorobromide or silver chloride, can be preferably used in the present invention. The phrase xe2x80x9ccontaining substantially no silver iodidexe2x80x9d means a silver iodide content of 1 mol % or less and preferably 0.2 mol % or less. Meanwhile, for such purposes as raising sensitivity to high illumination intensity, raising sensitivity to spectral sensitization, and raising storability of the photosensitive material, silver chloride-rich grains, which contain 0.01 to 3 mol % of silver iodide on the surface thereof, can be preferably used. Although the halogen compositions of the emulsions may be different or the same between grains, the use of an emulsion in which the halogen composition is the same between grains easily unifies the properties of the constituent grains.
The halogen composition of the interior of the silver halide emulsion grain may be selected from the following examples. A uniform grain structure in which any portion of the grain has the same composition; a so-called laminate structure in which the halogen compositions differ between the core of the interior of the silver halide grain and the shell (i.e., a layer or plural layers) surrounding the core; and a grain structure having inside or on the surface of the grain thereof non-layer portions which have different halogen compositions (if such portions are present on the grain, the portions are joined to the edge, corner, or surface of the grain). In comparison with the use of grains having a uniform structure, it is more advantageous to use a structure selected from the latter two structures in order to obtain a higher sensitivity and such structure is also preferable from the standpoint of pressure resistance. In the case where the silver halide grains have the above-mentioned structures, the boundary region having different halogen compositions may exhibit a clear boundary, an unclear boundary due to mixed crystals based on the difference in compositions, or a positively continuous change in structure.
In the silver chloride-rich emulsion for use in the present embodiment, the grain is preferably structured such that phases, in which silver bromide is localized, are present in a layer or non-layer state inside or on the silver halide grain as stated previously. The silver bromide content is preferably at least 10 mol % and more preferably 20 mol % in the halogen composition of the localized phase described above. The silver bromide content in the silver bromide-localized phase can be analyzed, for example, by means of an X-ray diffractometry (described, for example, in xe2x80x9cNew Experimental Chemistry Lecturesxe2x80x9d (Shin Jikken Kagaku Kouza) 6, edited by Chemical Society of Japan, Maruzen Co., Ltd.). These localized phases may be present inside the grain, on the edges of the grain surface, on the grain corners, or on the grain surface. An example of the localized phases is the localized phase epitaxially grown on the corner of a grain.
Further, in order to reduce replenishment amounts of a development processing solution, it is effective to further increase the silver chloride content of the silver halide emulsion. In such a case, an emulsion, which is composed of almost pure silver chloride and has a silver chloride content as high as 98 to 100 mol %, is preferably used.
The average grain size of the silver halide grains contained in the silver halide emulsion for use in the present invention (diameters of circles equivalent to the projected areas were deemed to be the grain sizes and the number average was obtained from the diameters) is preferably 0.1 to 2 xcexcm.
As to the grain size distribution, preferable is a so-called monodispersed grain system whose variation coefficient (which is obtained by dividing the statistical standard deviation of grain size distribution by the average grain size) is 20% or less, preferably 15% or less, and more preferably 10% or less. Further, for obtaining a broad latitude, it is a preferred practice to use a mixture of the monodispersed emulsions described above for the same layer or to form plural layers using the monodispersed emulsions described above.
The shape of the silver halide grain in the photographic emulsion may be selected from a regularly structured crystal such as a cube, tetradecahedron, or octahedron, an irregularly structured crystal such as a sphere or a tabular shape, and a complex made up of the foregoing. Further, the grains may be made up of a mixture of the crystals described above. Among these shapes, the grains in the present invention contain grains having the above-mentioned regularly structured crystals in a proportion of 50% or more, preferably 70% or more, and more preferably 90% or more.
Besides the emulsions described above, also preferably used is an emulsion in which the proportion of tabular grains, having an average aspect ratio (circle-equivalent diameter/thickness) of 5 or more and preferably 8 or more, exceeds 50% of the total grains in terms of projected areas.
The silver chloride(bromide) emulsions for use in the present invention can be prepared by the methods described in, for example, P. Glafkides, xe2x80x9cChimie et Physique Photographiquexe2x80x9d, Paul Montel, 1967; G. F. Duffin, xe2x80x9cPhotographic Emulsion Chemistryxe2x80x9d, Focal Press, 1966; and V. L. Zelikman et al., xe2x80x9cMaking and Coating Photographic Emulsionxe2x80x9d, Focal Press, 1964. That is, the preparation can be performed by any method selected from an acidic method, a neutral method, and an ammonia method. As to the method for causing a reaction between a soluble silver salt and a soluble halogen salt, any method selected from a single jet method, a double jet method, and a combination thereof may be employed. It is possible to employ a method in which grains are formed in an environment having an excess of silver ions (i.e., a so-called reverse mixing method). It is also possible to employ a method, namely a controlled double jet method, wherein the pAg of the liquid phase in which silver halide is formed is maintained at a constant value, as a method included in the double jet method. According to this method, it is possible to obtain a silver halide emulsion having grain crystals regularly formed and nearly uniform grain sizes.
It is preferable that a localized phase or substrate of the silver halide grain of the present embodiment contains a different metal ion or a complex ion thereof. Preferred examples of the ions are selected from ions or complexes of metals belonging to Group VI, II, or IIb of the Periodic Table, lead ions, and thallium ions. Ions of metals selected from iridium, rhodium, iron, and the like, and complex ions thereof can be used in combinations mainly for the localized phase. On the other hand, ions of metals selected from osmium, iridium, rhodium, platinum, ruthenium, palladium, cobalt, nickel, iron, and the like, and complex ions thereof can be used in combinations mainly for the substrate. The kinds and concentrations of the metal ions may be different between the localized phase and the substrate. Plural kinds of these metals may be used. In particular, it is preferable that iron and iridium compounds are present in the silver bromide-localized phase.
These compounds that provide metal ions are incorporated into the localized phase and/or other grain portion (substrate) of the silver halide grain, for example, by being added or dissolved in a gelatin aqueous solution, a halide aqueous solution, a silver salt aqueous solution, or other aqueous solution, or alternatively, by being added in a state of silver halide grains already containing the metal ion and dissolved, at the time when the silver halide grains are formed.
The incorporation of the metal ions that are used in the present embodiment into the grains of the emulsion can be carried out before grain formation, during grain formation, or immediately after grain formation. The timing of the incorporation can be changed depending on the grain portion into which the metal ions are incorporated.
The silver halide emulsion that is used in the present embodiment normally undergoes a chemical sensitization and a spectral sensitization.
Examples of the chemical sensitization include a chemical sensitization using a chalcogen sensitizer (specific examples thereof include a sulfur sensitization represented by the addition of an unstable sulfur compound, a selenium sensitization by the addition of a selenium compound, and a tellurium sensitization by the addition of a tellurium compound), a noble metal sensitization represented by a gold sensitization, a reduction sensitization, and a combination of the foregoing. The compounds described in JP-A-No. 62-215272, lower right column on page 18 to upper right column on page 22, are preferably used.
The effect of the constitution of the silver halide photosensitive material in the present embodiment becomes more evident when a chloride-rich silver halide emulsion that is gold-sensitized is used.
The emulsion for use in the present embodiment is a so-called surface latent image type emulsion in which latent images are formed mainly on the grain surface.
For prevention of fogging during manufacture, storage, or photographic processing or for the stabilization of photographic performances, the emulsion for use in the present embodiment may contain various compounds or precursors thereof. Specific examples of these compounds are preferably the compounds described in JP-A No. 62-215272, pages 39-72. Further, 5-arylamino-1,2,3,4-thiatriazole (in which the aryl residue has at least one electronxe2x80x94withdrawing group) described in EP 0447647 is also preferably used.
The spectral sensitization is carried out in order to impart spectral sensitivity in a desired wavelength region to the emulsion of the layers in the photosensitive material of the present invention.
In the photosensitive material of the present embodiment, examples of the spectral sensitizing dyes to be used for the spectral sensitization in blue, green, and red regions include the dyes described, for example, in F. M. Harmer, xe2x80x9cHeterocyclic compoundsxe2x80x94Cyanine dyes and related compoundsxe2x80x9d, John Wiley and Sons, New York, London, 1964. The specific examples of the compounds and the spectrally sensitizing methods described in JP-A No. 62-215272, upper right column on page 22 to page 38, are preferably used. As to the spectral sensitizing dye for red-sensitivity of silver halide emulsion grains having a high silver chloride content in particular, the spectral sensitizing dye described in JP-A No. 3-123340 is very desirable from the standpoint of stability, strength of adsorption, temperature dependence of exposure, etc.
In the photosensitive material of the present embodiment, sensitizing dyes described in JP-A No. 3-15049, upper left column on page 12 to lower left column on page 21, JP-A No. 3-20730, lower left column on page 4 to lower left column on page 15, EP 0,420,011, line 21 on page 4 to line 54 on page 6, EP 0,420,012, line 12 on page 4 to line 33 on page 10, EP 0,443,466, and U.S. Pat. No. 4,975,362 are preferably used.
In order to incorporate these spectral sensitizing dyes into silver halide emulsions, the dye may be directly dispersed in the emulsion, or alternatively, the dye may be added to the emulsion after the dye is dissolved in a solvent such as water, methanol, ethanol, propanol, methyl cellosolve, 2,2,3,3-tetrafluoropropanol, or a mixture thereof. Further, the dye may be made into solutions in the presence of an acid or base as described in Japanese Patent Application Publication (JP-B) Nos. 44-23389, 44-27555, and 57-22089, and others and the solution may be added to the emulsion, or alternatively, the dye may be made into a solution or colloidal dispersion in the presence of a surfactant as described in U.S. Pat. Nos. 3,822,135 and 4,006,025 and the solution or colloidal dispersion may be added to the emulsion. Further, the dye may be dissolved in a solvent such as phenoxyethanol which is substantially immiscible with water, and the solution may be dispersed in water or in a hydrophilic colloid. After that, the dispersion may be added to the emulsion. Furthermore, as described in JP-A Nos. 53-102733 and 58-105141, the dye may be dispersed directly in a hydrophilic colloid and the dispersion may be added to the emulsion. The timing to add the dye to the emulsion may be any stage of the manufacture of the emulsion hitherto known as useful. That is, the timing may be selected from the stages before grain formation of the emulsion, during grain formation, immediately after grain formation but before washing with water, before chemical sensitization, during chemical sensitization, immediately after chemical sensitization but before cooling the emulsion to solidify the grains, and during the preparation of a coating liquid. Most commonly, the addition is made after the completion of the chemical sensitization but before the coating operation. However, the dye may be added concurrently with the addition of a chemical sensitizer so that the chemical sensitization and spectral sensitization are carried out at the same time as described in U.S. Pat. Nos. 3,628,969 and 4,225,666. Further, the addition may be made before chemical sensitization or the addition may be made before the completion of the formation of silver halide grain precipitate to enable the start of spectral sensitization as described in JP-A No. 58-113928. Furthermore, the spectral sensitizing dye may be added in aliquots, that is, part of the dye may be added before chemical sensitization and the remainder may be added after chemical sensitization as disclosed in U.S. Pat. No. 4,225,666. Alternatively, the addition may be made at any time during the stage of silver halide grain formation according to the teachings found in, for example, U.S. Pat. No. 4,183,756. Particularly, it is preferable to add the sensitizing dye at the stage before washing with water or before chemical sensitization.
The amount to be added of the spectral sensitizing dye may vary within a wide range. The amount to be added is preferably in the range of 0.5xc3x9710xe2x88x926 to 1.0xc3x9710xe2x88x922 mole and more preferably in the range of 1.0xc3x9710xe2x88x926 to 5.0xc3x9710xe2x88x923 mole per mole of the silver halide.
In the present invention, where a sensitizing dye whose spectral sensitization sensitivity ranges from a red region to an infrared region is used, it is preferable to use a compound described in JP-A No. 2-157749, lower right column on page 13 to lower right column on page 22 together with the sensitizing dye. The use of such compound makes it possible to specifically raise the storability, processing stability, and supersensitization effect of the photosensitive material. Particularly, it is preferable to use the compound represented by the general formula (IV), (V), or (VI) in the above-mentioned patent literature. The amount to be used of the compound is in the range of 0.5xc3x9710xe2x88x925 to 5.0xc3x9710xe2x88x922 mole and preferably in the range of 5.0xc3x9710xe2x88x925 to 5.0xc3x9710xe2x88x923 mole per mole of the silver halide. The advantageous amount to be used of the compound falls within the range of 0.1 to 10,000 times and preferably within the range of 0.5 to 5,000 times the mole of the sensitizing dye.
Besides the use in a print system using an ordinary negative printer, the photosensitive material of the present embodiment is preferably used in digital scanning exposure using single-color high-density light such as a gas laser, light-emitting diode, semiconductor laser, or secondary high-frequency generating light source (SHG) combining a semiconductor laser or a solid-state laser using a semiconductor laser as an exciting light source with a nonlinear optical crystal. In order to make the system compact and inexpensive, it is preferable to use the semiconductor laser or secondary high-frequency generating light source (SHG) combining a semiconductor laser or a solid-state laser using a semiconductor laser as an exciting light source with a nonlinear optical crystal. Particularly, in order to design an apparatus which is compact and inexpensive and has long life and high stability, it is preferable to use a semiconductor laser and it is desirable to use a semiconductor laser as at least one of the light sources for exposure.
Where such a scanning light source for exposure is used, the peak of spectral sensitivity of the photosensitive material of the present invention can be set at will in accordance with the wavelength of the scanning light source to be used for exposure. In the SHG light source obtained by a combination of a solid-state laser using a semiconductor laser as an exciting light source or a semiconductor laser with a nonlinear optical crystal, the oscillation wavelength of the laser can be halved and therefore blue light and green light can be obtained. Accordingly, the peaks of spectral sensitivity of the photosensitive material can be present in three regions of ordinary blue, green, and red regions. In order to use a semiconductor laser as the light source so as to make the apparatus inexpensive, highly stable, and compact, it is preferable that at least two layers have peaks of spectral sensitivity at a wavelength of 670 nm or longer. This is because the light-emitting wavelength region of available semiconductor lasers, based on Group III-V elements that are inexpensive and stable, is only in the red to infrared region at the present time. However, since the oscillation of semiconductor lasers based on Group II-VI elements in the green and blue regions has been confirmed in laboratories, it is expected that these semiconductor lasers will become inexpensive and can be used in a stable manner when the production technology of semiconductor lasers develops. If this situation is realized, the necessity that at least two layers have peaks of spectral sensitivity at a wavelength of 670 nm or longer diminishes.
In the scanning exposure described above, the exposure time in which the silver halide in the photosensitive material is exposed to light is equal to the time required for exposing a certain minute area to the light. The minimum unit for controlling the light amount from corresponding digital data is used as this minute area and is designated as pixel. Accordingly, the exposure time per pixel varies depending on the pixel size. The pixel size depends on the pixel density and practically ranges from 50 to 2000 dpi. If the exposure time is defined as the time required for exposing the pixel size having a pixel density of 400 dpi, the exposure time is preferably 10xe2x88x924 second or less and more preferably 10xe2x88x926 second or less.
In the silver halide photosensitive material of the present embodiment, it is preferable to add a dye, which can be decolorized by a treatment and is described in European Patent EP 0337490A2, pp.27-76, (particularly an oxonol dye or a cyanine dye), to a hydrophilic colloid layer in order to prevent irradiation or halation or in order to raise safelight tolerance or the like.
Some of these water-soluble dyes impair color separation or safelight tolerance if the amounts to be used of the dyes are increased. The water-soluble dyes described in JP-A Nos. 5-127324, 5-127325, and 5-216185 are preferable as dyes that can be used without the impairment of the color separation.
In the present embodiment, a colored layer that can be decolorized by a treatment is used in place of the water-soluble dye or together with the water-soluble dye. The colored layer that can be decolorized by a treatment may be adjacent directly to an emulsion layer or may be in contact with an emulsion layer via an interlayer containing gelatin and a processing color mixing preventive such as hydroquinone. The colored layer is provided preferably underneath an emulsion layer (on the support side) which develops the same primary color as that of the colored layer. It is possible to provide colored layers corresponding to all primary colors and it is also possible to provide colored layers corresponding to arbitrarily selected primary colors. It is further possible to provide a colored layer having colors corresponding to a plurality of primary colors. As to the optical reflection density of the colored layer, the value of optical density at a wavelength which produces the highest optical density within a wavelength region for use in exposure (i.e., a visible light region of 400 to 700 nm in the exposure by an ordinary printer and the wavelength of a light source for scanning exposure in the case of scanning exposure) is preferably 0.2 or greater and 3.0 or smaller, more preferably 0.5 or greater and 2.5 or smaller, and particularly preferably 0.8 or greater and 2.0 or smaller.
For the formation of the colored layer, a conventionally known method can be employed. Examples of the method include the following methods. A method in which a dispersion of solid particles of a dye described in JP-A No. 2-282244, upper right column on page 3 to page 8 or a dispersion of solid particles of a dye described in JP-A No. 3-7931, upper right column on page 3 to lower left column on page 11 is incorporated into a hydrophilic colloid layer; a method in which an anionic dye is mordant-fixed to a cationic polymer; a method in which a dye is adsorbed to grains of a silver halide or the like to thereby fix the dye inside a layer; and a method in which colloidal silver is used as described in JP-A No. 1-239544. As an example of a method for dispersing particles of a dye in a state of solid particles, a method for incorporating dye particles, which are substantially insoluble in water at least at a pH of 6 or less but substantially soluble in water at least at a pH of 8or greater, is described in JP-A No. 2-308244, pp.4-13. An example of a method for mordant-fixing an anionic dye to a cationic polymer is described in JP-A No. 2-84637, pp.18-26. A method for preparing colloidal silver as a light absorber is disclosed in U.S. Pat. Nos. 2,688,601 and 3,459,563. Among these methods, a method for incorporating dye particles and a method using colloidal silver are preferable.
As to the binder or protective colloid that can be used in the present embodiment, the use of gelatin is advantageous. But other hydrophilic colloids can be used singly or together with gelatin. The use of gelatin having a low calcium content is preferable. The calcium content is preferably 800 ppm or less and more preferably 200 ppm or less. In order to prevent the growth of mildew or other bacteria in the hydrophilic colloid layer, it is preferable to add a mildew-proofing agent such as the one described in JP-A No. 63-271247.
When the photosensitive material of the present embodiment undergoes printer-exposure, it is preferable to use a band-strip filter described in U.S. Pat. No. 4,880,726. The use of this filter eliminates light-related color-mixing and remarkably enhances color reproducibility.
After exposure, the photosensitive material undergoes a conventional color developing treatment. In the present embodiment, it is preferable to carry out a bleach-fixing treatment after the color developing treatment for rapid processing. Particularly where the above-described emulsion having a high silver chloride content is used, the pH of the bleach-fixing solution is preferably about 6.5 or less, more preferably about 6 or less, for such purpose as acceleration of desilvering reaction.
As to the silver halide emulsion, and components such as a different metal ion species to be doped into the silver halide grain, a preservative stabilizer or fogging inhibitor of the silver halide emulsion, a method for chemical sensitization (sensitizer), a method for spectral sensitization (spectral sensitizer), a yellow coupler and a magenta or cyan coupler that can be used together and a method for emulsifying these couplers, a color-image preservation improving agent (a stain inhibitor or browning inhibitor) a dye (colored layer), and gelatin as well as the layer construction of the photosensitive material and pH of the coating layer of the photosensitive material, all for use in the present embodiment, prefarable reference is made to those described in the patent literatures, EP 0,335,660A2 (JP-A No. 2-139544) in particular, and shown in the following Tables 1 to 5. Further, those described in JP-A Nos. 7-104448, 7-77775, and 7-301895 are also preferably used.
It is preferable that the cyan, magenta, or yellow coupler is impregnated into a loadable latex polymer (e.g., as in U.S. Pat. No. 4,203,716) in the presence (or in the absence) of the high-boiling-point organic solvent described in the tables or is dissolved in the high-boiling-point organic solvent together with a polymer insoluble in water but soluble in an organic solvent; and, after that, the coupler is emulsified and dispersed in a hydrophilic colloid aqueous solution.
Examples of the preferably usable polymer insoluble in water but soluble in an organic solvent include homopolymers and copolymers described in U.S. Pat. No. 4,857,449, columns 7 to 15, and International Patent Laid-Open WO88/00723, pages 12 to 30. The use of methacrylate polymers or acrylamide polymers, particularly acrylamide polymers, is more preferable from such standpoint as image stability.
In the photosensitive material of the present invention, it is preferable to use an image-preservation improving agent, such as the one described in European Patent EP 0277589A2, together with the coupler. Particularly, combination of the image-preservation improving agent with a pyrazoloazole coupler or pyrrolotriazole coupler is preferable.
That is, it is preferable to use a compound which is described in the above-mentioned patent literature and which chemically combines with an aromatic amine-based developing agent remaining after color development processing to thereby form a chemically inert and substantially colorless compound and/or a compound which is described in the above-mentioned patent literature and which chemically combines with the oxidized form of an aromatic amine-based developing agent remaining after color development processing to thereby form a chemically inert and substantially colorless compound, singly or in combination thereof. This is preferable for example from the standpoint of the prevention of stain formation due to a coloring dye formation reaction with the developing agent or the oxidized form thereof remaining in the film during storage after processing and also from the standpoint of the prevention of other side effects.
As to the cyan couplers, preferred examples thereof include, besides the diphenylimidazole-based cyan couplers described in JP-A No. 2-33144, 3-hydroxypyridine-based cyan couplers described in European Patent EP 0 333185A2 (among these couplers, a 2-equivalent coupler, which is prepared by providing a chlorine-leaving group to an exemplary coupler (42), a coupler (6), and a coupler (9) are particularly preferable), cyclic active methylene-based cyan couplers described in JP-A No. 64-32260(among these couplers, exemplary couplers (3), (8), and (34) are particularly preferable), pyrrolopyrazole-type cyan couplers described in European Patent EP 0456226A1, pyrroloimidazole-type cyan couplers described in European Patent EP 0484909, and pyrrolotriazole-type cyan couplers described in European Patent EP 0484909. Among these couplers, pyrrolotriazole-type cyan couplers are particularly preferable.
As to the yellow couplers, preferred examples thereof include, besides the compounds described in known literatures in the tables, acylacetamide-type yellow couplers which have a 3- to 5-membered cyclic structure in the acyl group and are described in European Patent EP 0447969A1, malondianilide-type yellow couplers having a cyclic structure described in European Patent EP 0482552A2, and acylacetamide-type yellow couplers having a dioxane structure described in U.S. Pat. No. 5,118,599. Among these couplers, a acylacetamide-type yellow coupler whose acryl group is a 1-alkylcyclopropane-1-carbonyl group and a malondianilide-type yellow coupler in which one of the anilides constitutes an indoline ring are particularly preferable. These couplers may be used singly or in combinations.
As to the magenta couplers for use in the present embodiment, 5-pyrazolone-based magenta couplers or pyrazoloazole-based magenta couplers as described in known literatures in the tables are used. Among these couplers, preferable are a pyrazolotriazole coupler which has a secondary or tertiary alkyl group linked directly to a 2-, 3-, or 6-position of the pyrazolotriazole ring and is described in JP-A No. 61-65245, a pyrazolotriazole coupler which has a sulfonamide group in the molecule and is described in JP-A No. 61-65246, a pyrazolotriazole coupler which has an alkoxyphenylsulfonamide ballast group and is described in JP-A No. 61-147254, and a pyrazolotriazole coupler which has an alkoxy group or aryloxy group linked to a 6-position and is described in described in European Patent Nos. 226,849A and 294,785A.
As to the processing methods of the color photosensitive materials of the present embodiment, preferred examples thereof include, in addition to the methods listed in the tables, processing materials and processing methods, described in JP-A No. 2-207250, lower right column, line 1, on page 26 to upper right column, line 9, on page 34 and in JP-A No. 4-97355, upper left column, line 17, on page 5 to lower right column, line 20, on page 18, are preferable.
As to the methods for development-processing the color photosensitive materials of the present embodiment, a heat development system without using a processing liquid can be used besides conventional wet-processes such as a method which uses a developing solution containing an alkali agent and a developing agent for the processing and a method in which a developing agent is incorporated in the photosensitive material so that development is carried out by using an activator liquid, for example an alkaline solution, containing no developing agent. In particular, the activator system is preferable because of ease in handling, less disadvantages at the time of waste water disposal, and safety on environments.
In the activator system, a hydrazine-type compound described in, for example, JP-A No. 8-234388, 9-152686, 9-152693, 9-21181, and 9-160193, is preferable as the developing agent or precursor thereof to be incorporated in the photosensitive material.
Also preferably used is a development method in which the coating amount of silver of a photosensitive material is reduced and image amplification (intensification) is carried out using hydrogen peroxide. In particular, use of this method in an activator method is preferable. More specifically, preferably used are the methods which are described in JP-A Nos. 8-297354 and 9-152695 and use an activator solution containing hydrogen peroxide.
In the activator method, the photosensitive material after being treated with an activator solution normally undergoes a desilvering treatment. However, according to an image amplification treatment using a photosensitive material having a low silver content, the desilvering treatment can be omitted and a simple treatment such as washing with water or stabilization can be performed. In a method in which image information is read by a scanner or the like, a processing mode that does not require a desilvering treatment can be employed even when a photosensitive material having a high silver content such as a photographing material is used.
In the present embodiment, materials for activator solutions, desilvering solutions (bleach/fixing solutions) and rinsing and stabilizing solutions as well as treating methods using these solutions can be conventionally known ones. Preferably, those described in Research Disclosure, Item 36544 (September, 1994), pp.536 to 541, and JP-A No. 8-234388 can be used.
The high-boiling-point organic solvent according to the present embodiment is also preferably used in a photosensitive material having a magnetic recording layer for the advanced photo-system. Further, the high-boiling-point organic solvent according to the present embodiment can also be applied to a system in which heat development is carried out using a small amount of water or to a perfectly dry system in which heat development is carried out and entirely no water is used. Details of these systems are described in JP-A Nos. 6-35118, 6-17528, 56-146133, 60-119557, 1-161236, and so on.
The silver halide photosensitive material of the present invention includes not only a photosensitive material for forming colored images but also a photosensitive material for forming monotone images including black-and-white images.
The silver halide photosensitive material according to the present invention is most preferably applied to a color photosensitive material, although the silver halide photosensitive material according to the present invention is preferably applied to color photosensitive materials (e.g., color paper, display photosensitive materials, color photosensitive materials for cinema, instant photographic photosensitive materials including a dye diffusion transfer system (DTR), and photosensitive materials for heat development systems thereof) as well as to black-and-white photosensitive materials including general-purpose black-and-white photosensitive materials, micro, wash-off, medical, or industrial X-ray photosensitive materials, and printing photosensitive materials (including those for use in a silver salt diffusion transfer system and a dry systems using silver behenate or the like).
Where the compounds represented by the general formulae (a) to (d) are applied to color paper, the photosensitive material described in JP-A No. 11-7109 is preferable. Particularly, the descriptions in paragraphs [0071] to [0087] of JP-A No. 11-7109 are fully incorporated herein as part of the specification of the present invention.
Where the compounds represented by the general formulae (a) to (d) are applied to color negative films, the description in JP-A No. 11-305396, paragraphs [0115] to [0217], is preferably applied and incorporated herein as part of the specification of the present invention.
Where the compounds represented by the general formulae (a) to (d) are applied to color reversal films, the description in JP-A No. 11-84601, paragraphs [0018] to [0021], is preferably applied and incorporated herein as part of the specification of the present invention.